—Imprivata, a Lexington, MA-based maker of healthcare software, says it has confidentially filed paperwork for an IPO. The company’s announcement is part of the newer wave of IPO filings under the federal JOBS Act, which lets companies of less than $1 billion in revenue file their draft registrations secretly. Imprivata’s investors include Polaris Partners, Highland Capital Partners, General Catalyst, and SAP Ventures.